Refactor MutatorHostClient from LayerTreeHost to LayerTree.

ui/compositor/compositor.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/compositor.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <deque>
@@ skipping 197 matching lines @@
   params.task_graph_runner = context_factory_->GetTaskGraphRunner();
   params.settings = &settings;
   params.main_task_runner = task_runner_;
   params.animation_host = cc::AnimationHost::CreateMainInstance();
   host_ = cc::LayerTreeHost::CreateSingleThreaded(this, &params);
   UMA_HISTOGRAM_TIMES("GPU.CreateBrowserCompositor",
                       base::TimeTicks::Now() - before_create);
 
   animation_timeline_ =
       cc::AnimationTimeline::Create(cc::AnimationIdProvider::NextTimelineId());
-  host_->animation_host()->AddAnimationTimeline(animation_timeline_.get());
+  host_->GetLayerTree()->animation_host()
+      ->AddAnimationTimeline(animation_timeline_.get());
 
   host_->SetRootLayer(root_web_layer_);
   host_->set_surface_client_id(surface_id_allocator_->client_id());
   host_->SetVisible(true);
 }
 
 Compositor::~Compositor() {
   TRACE_EVENT0("shutdown", "Compositor::destructor");
 
   CancelCompositorLock();
   DCHECK(!compositor_lock_);
 
   FOR_EACH_OBSERVER(CompositorObserver, observer_list_,
                     OnCompositingShuttingDown(this));
 
   FOR_EACH_OBSERVER(CompositorAnimationObserver, animation_observer_list_,
                     OnCompositingShuttingDown(this));
 
   if (root_layer_)
     root_layer_->ResetCompositor();
 
   if (animation_timeline_)
-    host_->animation_host()->RemoveAnimationTimeline(animation_timeline_.get());
+    host_->GetLayerTree()->animation_host()
+      ->RemoveAnimationTimeline(animation_timeline_.get());
 
   // Stop all outstanding draws before telling the ContextFactory to tear
   // down any contexts that the |host_| may rely upon.
   host_.reset();
 
   context_factory_->RemoveCompositor(this);
   if (context_factory_->GetSurfaceManager()) {
     for (auto& client : surface_clients_) {
       if (client.second) {
         context_factory_->GetSurfaceManager()
@@ skipping 308 matching lines @@
                     observer_list_,
                     OnCompositingLockStateChanged(this));
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui